AOV control systems are used mainly to control the ventilation of smoke in a fire. Changes to building regulations were made due to the results of investigations into smoke inhalation. When a detector or call point is triggered an AOV control system will open actuators, windows or vents to create ventilation. This clears smoke for people leaving the building and vents smoke out of the area that has been triggered. The provisional standard that is now available for reference is EN:12101.